Sperm are single-purposed: They're optimized to get to an egg and inseminate it. But that doesn't mean there isn't more to this cell than meets the ovum. Sperm, along with its travelling companion, semen, are surprisingly versatile and adaptable substances. Here are eight unconventional things you can do with human sperm.

Those looking to take their culinary skills to the next level should check out a book by Fotie Photenhauer called Natural Harvest, a collection of semen-based recipes. The book description:

Semen is not only nutritious, but it also has a wonderful texture and amazing cooking properties. Like fine wine and cheeses, the taste of semen is complex and dynamic. Semen is inexpensive to produce and is commonly available in many, if not most, homes and restaurants. Despite all of these positive qualities, semen remains neglected as a food.

This book hopes to change that.

Once you overcome any initial hesitation, you will be surprised to learn how wonderful semen is in the kitchen. Semen is an exciting ingredient that can give every dish you make an interesting twist. If you are a passionate cook and are not afraid to experiment with new ingredients - you will love this cook book!

3. Painting

Artist Martin Von Ostrowski is known for using bodily fluids as his paint mediums (including his infamous portrait of Hitler made from his own excrement). Back in 2008, Von Ostrowski put out an exhibition at the Gay Museum in Berlin in which he featured works painted with his own semen. A single painting requires about 40 ejaculations, which, given the size of the exhibition, suggests that he needed to ejaculate at least 1,000 times. Impressive! Von Ostrowski is able to keep these large quantities of sperm fresh by freezing it.

4. Invisible ink

Back during World War I, the British Secret Intelligence Service (MI6) discovered that semen could act as an effective invisible ink. In June 1915, Walter Kirke, deputy head of military intelligence in France, wrote in his diary that chief Mansfield Cumming (yes), was "making enquiries for invisible inks at the London University." Rumor at the time had it that semen worked particularly well, and follow-up studies showed that it did not react to the usual methods of detection (including iodine vapor). It was also readily available for any intrepid secret service agent willing to make the sacrifice. The practice went into use, but it was noted that on at least one occasion that an agent had to be reminded to use only fresh supplies of the "ink" when people started noticing an unusual smell.

5. An anti-Depressant for women

Another potential application for semen is its use as an anti-depressant. This idea is quite controversial — but there is a modicum of scientific evidence to support it. A study done back in 2002 showed that women who were directly exposed to semen were less depressed. The researchers concluded that this was on account of mood-altering hormones in the semen being absorbed through the vagina — and that they had ruled out other explanations (New Scientist didn't entirely agree — proposing a number of their own). That said, as Jesse Bering has pointed out, "there's good in this goo":

In fact, semen has a very complicated chemical profile, containing over 50 different compounds (including hormones, neurotransmitters, endorphins and immunosupressants) each with a special function and occurring in different concentrations within the seminal plasma. Perhaps the most striking of these compounds is the bundle of mood-enhancing chemicals in semen...Such anxiolytic chemicals include, but are by no means limited to, cortisol (known to increase affection), estrone (which elevates mood), prolactin (a natural antidepressant), oxytocin (also elevates mood), thyrotropin-releasing hormone (another antidepressant), melatonin (a sleep-inducing agent) and even serotonin (perhaps the most well-known antidepressant neurotransmitter).

6. Ovulation control

A recent study at the University of Saskatchewan has discovered that a protein in semen acts on the female brain to prompt ovulation — and that it's the same molecule that regulates the growth, maintenance, and survival of nerve cells. As a result, it's very possible that semen acts as a hormonal signal, working through the hypothalamus of the female brain and the pituitary gland. This in turn triggers the release of other hormones that signal the ovaries to release an egg.

In what gives new meaning to the term "hard drive", human sperm — a transmitter of DNA — could be used to store information — a lot of information. We recently reported on a breakthrough by Sriram Kosui and his team at Harvard and Johns Hopkins in which he devised a technique for archiving information in DNA. The process, which takes advantage of DNA's data sequencing attributes, could be used to store as much as one petabyte of data (one petabyte = 1,024 terabytes) in a volume of 1.5 mg of DNA. Because genetic information can be packaged in three dimensions, that equates to a storage volume of about one cubic millimeter — so you'll finally have a secure and ironic place to store your massive digital porn collection.